Conventionally, there have been known receivers of a superheterodyne system having adopted a low-IF scheme, which makes the local oscillation frequency closer to the reception frequency, thereby making the intermediate frequency considerably lower than the reception frequency. In the low-IF scheme, because the frequencies of a desired received signal and of an image signal are close to each other, the removal of the image signal is one of the tasks in configuring receivers. A technique using a complex BPF is disclosed in order to remove the image signal.